Shading Analysis

What is shading analysis

Shading analysis is the process of quantifying solar PV yield loss caused by obstructions blocking direct sunlight reaching the array. Obstructions include trees, neighbouring buildings, chimneys, parapets, water tanks, satellite dishes, mounting frames and inter-row shadows from other panels. Shading analysis uses sun-path geometry combined with three-dimensional obstruction mapping to compute the time-dependent shading pattern across the year.

Shading impact on PV is non-linear. A small shadow on one cell can cut a series-connected string’s output by 30 to 90 percent without bypass diode protection. Modern modules include bypass diodes that limit this loss, but partial shading still causes significant yield reduction. System-level mitigation includes string splitting across MPPT inputs, microinverters and DC optimisers.

For Indian rooftop solar, shading analysis is essential because urban rooftops are crowded with obstructions. Trees in residential settings, chimneys, neighbouring buildings, water tanks and parapets all contribute to shading loss. Utility-scale installations care about inter-row shading from system geometry.

Why shading analysis matters

Yield accuracy. Without shading analysis, P50 yield estimates are systematically optimistic.

Design optimisation. Module placement, tilt and string layout decisions depend on shading patterns.

Equipment selection. Heavy shading favours microinverters or DC optimisers.

Customer expectations. Honest shading projections prevent disappointment after commissioning.

PPA accuracy. PPA generation commitments should be based on shading-corrected yield.

System ROI. Shading loss directly reduces revenue.

How shading analysis works

1. Map site location and orientation.
2. Identify all obstructions (trees, buildings, structures) with height and position.
3. Generate a 3D model in shading analysis software.
4. Compute sun-path geometry for the year.
5. Calculate shadow patterns hour by hour.
6. Quantify shading loss per module or per string.
7. Aggregate to annual shading loss percentage.

Technical deep dive

Shading loss components

Software tools

Hand calculation: maximum tree shading

For a tree of height H at distance D south of a south-facing array:

Inter-row shading

Row pitch (m) to avoid noon winter shading: Pitch = panel_height × cos(tilt) + panel_height × sin(tilt) / tan(altitude_min)

For 2.3 m panel, 25° tilt, Delhi: Pitch = 2.3 × cos(25°) + 2.3 × sin(25°) / tan(38°) = 2.08 + 1.24 = 3.32 m

Most utility plants use 3.5 to 4 m pitch to balance shading and land use.

Shading mitigation techniques

Real-world applications

Residential rooftop solar planning.

C&I rooftop with chimney and parapet obstructions.

Carport design.

Utility plant inter-row spacing.

Floating solar (limited shading).

BIPV with adjacent building obstructions.

Common shading problems

Water tank shading critical noon hours.

Tree growth over years increasing shading.

Neighbouring building expansion creating new shading.

Inter-row shading from undersized row spacing.

Self-shading from oversized panels close to parapets.

Best practices

Conduct shading analysis at design stage with software.

Include conservative tree growth projection (10 to 15 years).

Consider seasonal sun paths, not just summer.

Avoid placing panels in regions with > 5 percent annual shading loss.

Use microinverters or DC optimisers where shading unavoidable.

Document shading loss in design report.

Update analysis if site changes.

Comparison: shading mitigation

Indian market context

Indian rooftop shading typically comes from water tanks, parapets, adjacent buildings, antennas and trees.

PM Surya Ghar installers often conduct visual shading assessment; formal software analysis is rare for residential.

C&I and utility projects use PVsyst or Helioscope for bankable shading analysis.

ALMM-listed modules ship with three bypass diodes per module standard; six-diode designs growing for premium installations.

Microinverter adoption (Enphase) is increasing in shading-heavy Indian residential markets.

Standards and certifications

Common mistakes

Skipping shading analysis on “clean” rooftops, missing seasonal obstructions.

Ignoring tree growth over project life.

Using summer-only analysis, missing winter sun angle issues.

Inadequate row spacing on ground-mount plants.

Mixed-orientation strings without per-MPPT separation.

Trusting brochure shading claims without site-specific analysis.

Key takeaways

Shading analysis quantifies yield loss from obstructions. Software tools like PVsyst and Helioscope provide bankable analysis. Annual shading loss above 5 percent triggers design changes. Mitigation includes string splitting, DC optimisers and microinverters. Indian rooftops typically have non-trivial shading from tanks, parapets and trees, making shading analysis essential at the design stage.

Further reading

For how Shading Analysis plays out in real projects, these guides go deeper:

• Solar Shading Analysis Software Poland: 2026 Guide
• Solar Shading Analysis Software Saudi Arabia: 2026 Guide
• Solar Shading Analysis Software Singapore: 2026
• Solar Shading Analysis Software Canada: 2026 Guide

Sources

• PVsyst software documentation.
• Helioscope software documentation.
• NREL System Advisor Model (SAM) documentation.
• IEC 61724-1, Performance monitoring.
• MNRE Design Guidelines for Solar PV Plants.
• Aurora Solar documentation.
• Duffie J. A., Beckman W. A., Solar Engineering of Thermal Processes, Wiley.
• ITRPV Roadmap on shading mitigation.
• IEA PVPS Task 13 Report on PV Performance.